The present invention relates to fiber optic pressure transducers, and more specifically to systems for accurately calibrating such devices to correlate the value of pressure being measured to the intensity of light transmitted through an optical fiber.
Pressure measurements are made in a variety of applications by means of fiber optic pressure sensors in which a movable portion of a sensing tip at the end of a hollow tube is deformed or deflected in accordance with the pressure differential on opposite sides thereof. One or more optical fibers extend through the tube and carry light from a source outside the tube to a reflecting surface inside the sensing tip, and thence back through the fiber(s) to means for measuring the intensity of the reflected light. Means are provided in the sensing tip for attenuating the light intensity in accordance with the pressure differential, whereby the measured intensity of the light returned through the fiber(s) may be translated into a measurement of the pressure at the sensing tip.
The foregoing presupposes, of course, that the relationship between measured light intensity and pressure is known over the range of pressures to be measured. This necessitates some manner of initialization and calibration of the system in order that the pressure exerted upon a given sensor tip may be properly correlated with the measured intensity of reflected light.
It is an object of the present invention to provide an accurate system for initializing and calibrating a fiber optic pressure transducer having a sensor tip with light attenuating means related to pressure differential inside and outside the tip.
A further object is to provide such a calibration system which is economical in cost and simple to operate.
Another object is to provide a system which permits sensor tips of a fiber optic pressure measurement system to be individually calibrated in terms of the pressure-light intensity relationship in a short time.
The principal object is to provide a fiber optic pressure sensing tip calibration system having all of the foregoing advantages, i.e., accuracy, economy, simplicity and speed of operation.
Other objects will in part be obvious and will in part appear hereinafter.